Pick-and-place head and method for picking work-pieces

ABSTRACT

A pick-and-place head for picking a plurality of work-pieces from at least one first location and for placing the plurality of work-pieces at least one second location is disclosed. The pick-and-place head exhibits a plurality of nozzles, wherein each nozzle is configured to engage one of the work-pieces by action of a vacuum. At least one nozzle has an individual vacuum supply and at least two further nozzles have a shared vacuum supply. A corresponding method is also disclosed, the method including the steps of approaching at least one of the plurality of work-pieces with a respective nozzle and then starting generation of a vacuum at each respective nozzle. The generation of vacuum in at least one nozzle is achieved by an individual vacuum supply, and generation of vacuum in at least two further nozzles is achieved by a shared vacuum supply of the at least two further nozzles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/409,156, filed on Jan. 18, 2017, which application is a continuationof U.S. patent application Ser. No. 14/594,810, filed on Jan. 12, 2015,which application was filed under 35 U.S.C. § 111(a) and § 365(c) as acontinuation of International Patent Application No. PCT/US2014/064841,filed on Nov. 10, 2014, which application claims the benefit of U.S.Provisional Patent Application No. 61/909,184, filed on Nov. 26, 2013,which applications are incorporated herein by reference in theirentireties.

FIELD

The present invention relates to a pick-and-place head for pickingwork-pieces from one location and placing them at a different location,as well as to a corresponding method. More specifically the presentinvention relates to a pick-and-place head and corresponding methodwherein the picking of work-pieces is by action of a vacuum.

BACKGROUND

Manufacturing of a product or assembly of some apparatus generallyinvolves the handling of work-pieces, for example components to beassembled. In particular, these work-pieces need to be transportedbetween different locations, like assembly stations, inspectionstations, packaging stations, or transport means as they proceed throughthe manufacturing process. In modern automated or semi-automatedmanufacturing, such handling of work-pieces is usually done by robots. Alarge number of components may be handled in parallel. For example,electronic components are often transported in molded matrix carriers,for example JEDEC trays. The electronic components are situated in thepockets, or cells, of the trays. Placing components into the pockets orpicking components from the pockets for transferring them to a differentlocation, i.e. for inspection or assembly, is usually done bypick-and-place robots. A pick-and-place robot typically comprises one orseveral so-called grippers (or pickers) that can pick-up an electroniccomponent from a pocket of a tray and also place an electronic componentinto a pocket of a tray. The gripper may be mechanically clamping theelectronic component or, more commonly, be using vacuum nozzles.

In order to increase throughput, pick-and-place robots are oftenequipped with multiple grippers such that several components can bepicked up or placed in parallel. Common configurations arepick-and-place heads that have enough grippers to pick up an entire rowof components at the same time or in some cases two entire rows ofcomponents at the same time.

In a typical manufacturing process most pockets of a tray contain onecomponent that can be picked up by a gripper. There are, however,usually also a few pockets per tray that are empty or pockets thatcontain an incorrectly placed component, e.g. tilted or rotated. Fromsuch pockets no components can be picked up and a vacuum nozzle that isplaced above such a pocket will not attain vacuum. Conventionalmulti-nozzle/gripper pick-and-place robots using vacuum nozzles havetherefore independent/individual vacuum/blow-off supply lines along withindividual vacuum sensors for each nozzle such that if there is a nozzleat an empty pocket or at an incorrectly placed component, where novacuum can be attained, other nozzles will not be affected but can pickup components by vacuum, hence, operate correctly.

That means that in order to increase the number of grippers or nozzles,the number of vacuum supplies and of vacuum sensors has to be increasedas well. Additional hardware on the pick-and-place head increases themass of the pick-and-place head. For high throughput, however, highaccelerations are needed, hence, higher mass is undesirable, and besidesalso increases costs. And in particular when upgrading existing headswith additional nozzles, many parts of the head need to be modified orchanged, especially so that the number of vacuum supplies and of vacuumsensors can be increased as required.

While the above has described a typical situation for handlingelectronic components using vocabulary current in that field, theproblem shown in the above example is more general. Wherever largenumbers of components or work-pieces, especially components of at leastroughly the same geometry, need to be handled during manufacturing,robots, or more generally, pick-and-place devices, may be employed thatcan pick or place more than one component at once. Using vacuum appliedto the work-pieces via nozzles for picking the work-pieces is awidespread concept. For placing a work-piece, or dropping a work-piecefrom a nozzle, the vacuum for the corresponding nozzle is cancelled,additionally a burst of gas, usually air, may be used to actively blowthe work-piece from the nozzle.

As has already been indicated above, if a pick-and-place head is to bemodified to change the number of nozzles it exhibits so that the numberof work-pieces it can handle at once is changed, in typicalpick-and-place heads major reconfigurations are required, as each nozzlehas its separate vacuum supply, usually with corresponding vacuumsensor. Furthermore, providing separate vacuum supplies and vacuumsensors for each nozzle renders the configuration of the pick-and-placehead quite complex.

SUMMARY

The present invention comprises a pick-and-place head for transporting aplurality of work-pieces from at least one first location to at leastone second location, the pick-and-place head having a plurality ofnozzles with each nozzle configured to engage one of the plurality ofwork-pieces, at least one independent vacuum supply configured to attachto one nozzle of the plurality of nozzles, and, at least one sharedvacuum supply configured to attach to at least two nozzles of theplurality of nozzles not attached to the at least one independent vacuumsupply.

The present invention also comprises a pick-and-place head fortransporting a plurality of work-pieces from at least one first locationto at least one second location, the pick-and-place head having aplurality of nozzles with each nozzle configured to engage one of theplurality of work-pieces, the plurality of nozzles arranged in rows withat least a first and second row, a plurality of independent vacuumsupplies with each configured to attach to each nozzle of the pluralityof nozzles in the first row, a shared vacuum supply configured to attachto the second row of nozzles, a plurality of vacuum sensors configuredto indicate whether or not a sufficient force is being applied to theplurality of work-pieces, wherein the shared vacuum supply and each ofthe plurality of independent vacuum supplies have one vacuum sensor.

The present invention also comprises a pick-and-place device having apick-and-place head moveable by operation of the pick-and-place device,the pick-and-place head having a plurality of nozzles with each nozzleconfigured to engage one of a plurality of work-pieces by action of avacuum, wherein at least one nozzle of the plurality of nozzles has anindividual vacuum supply and at least two further nozzles of theplurality of nozzles have a shared vacuum supply.

The present invention also comprises a method for picking a plurality ofwork-pieces with a plurality of nozzles by action of a vacuum, forplacing the work-pieces at a different location, the method includingthe steps of approaching at least one of the plurality of work-pieceswith a respective nozzle, and generating a vacuum at each respectivenozzle, wherein the generating step is achieved in at least one of theplurality of nozzles by an individual vacuum supply of the at least oneof the plurality of nozzles and in at least two further nozzles of theplurality of nozzles by a shared vacuum supply of the at least twofurther nozzles.

The present invention also comprises a method for picking a plurality ofwork-pieces with a plurality of nozzles by action of a vacuum, forplacing the work-pieces at a different location, wherein the pluralityof work-pieces and the plurality of nozzles are arranged in respectiverows, the nozzles of one first row of nozzles each having an individualvacuum supply, the nozzles of the remaining at least one second row ofnozzles having a shared vacuum supply, the method including the stepsof: a) positioning, by relative movement between the nozzles and thework-pieces, each row of nozzles above a row of work-pieces; b)attempting to pick up a respective work-piece with each nozzle; c)placing the picked-up work-pieces at a different location; d) verifyingif work-pieces failed to be picked up in step b); e1) positioning thefirst row of nozzles over a verified work-piece that has been verifiedby step d) as being failed to be picked up; f1) picking up the verifiedwork-piece with a nozzle of the first row of nozzles and placing theverified work-piece at the different location intended for it in stepc); g1) repeating steps e1) and f1) until no verified work-pieces whichfailed to be picked up in step b) remain; e2) testing, if step d) doesnot indicate work-pieces that failed to be picked up, if at least asmany rows of work-pieces remain to be picked up as there are rows ofnozzles, and if so, repeat from step a), else consider any remainingrows of work-pieces as if they had failed to be picked up in step b) andproceed from step e1), picking up all the work-pieces in such a row withthe nozzles in the first row of nozzles.

A general object of the present invention is to provide a pick-and-placehead of simpler configuration, which can easily be reconfigured in orderto change the number of work-pieces that can be handled at once, andwhich nonetheless provides for efficient and reliable handling of allthe work-pieces to be processed.

Another object of the present invention is to provide a method forhandling plural work-pieces at once in an efficient and reliable manner.

The object with regard to the pick-and-place head is achieved by apick-and-place head for picking a plurality of work-pieces from at leastone first location and for placing the plurality of work-pieces in atleast one second location, the pick-and-place head exhibiting aplurality of nozzles, each nozzle of the plurality of nozzles configuredto engage one of the plurality of work-pieces by action of a vacuum,wherein at least one nozzle of the plurality of nozzles has anindividual vacuum supply and at least two further nozzles of theplurality of nozzles have a shared vacuum supply.

The object with regard to the method is achieved by a method for pickinga plurality of work-pieces with a plurality of nozzles by action of avacuum, for placing the work-pieces at a different location, the methodincluding the steps of approaching at least one of the plurality ofwork-pieces with a respective nozzle and then starting generation of avacuum at each respective nozzle, wherein generation of a vacuum in atleast one of the plurality of nozzles is achieved by an individualvacuum supply of the at least one of the plurality of nozzles andgeneration of a vacuum in at least two further nozzles of the pluralityof nozzles is achieved by a shared vacuum supply of the at least twofurther nozzles.

A pick-and-place head according to the invention exhibits a plurality ofnozzles, each of which is configured to engage one of the plurality ofwork-pieces by action of a vacuum. According to the invention at leastone nozzle of the plurality of nozzles has an individual vacuum supplyand at least two further nozzles of the plurality of nozzles have ashared vacuum supply. An individual vacuum supply for a nozzle meansthat the vacuum supply for the nozzle is independent of the vacuumsupply for different nozzles, and in particular implies that if afailure to achieve a sufficient degree of vacuum occurs at one or pluralother nozzles of the pick-and-place head, this failure does not affectthe nozzle with the individual vacuum supply. As at least two furthernozzles have a shared vacuum supply, there is, obviously, no need forproviding individual vacuum supplies for each of these further nozzles,thus leading to a simpler configuration of the pick-and-place head. Ashared vacuum supply by itself, however, has one significantdisadvantage. If a sufficient degree of vacuum is not achieved at one ofthe nozzles sharing a vacuum supply, this will also affect the vacuum atthe other nozzles connected to the shared vacuum supply, usually leadingto a breakdown of vacuum or failure to achieve a sufficient vacuum atthese other nozzles. A failure to achieve vacuum at a single nozzle,affecting then all other nozzles connected to the common vacuum supply,for example occurs if a nozzle is to pick up a work-piece from aposition where it is supposed to be, for example a specific pocket of atray, but the work-piece is not there, i.e. not in the pocket, or isinadequately positioned relative to the nozzle so that it cannotproperly seal the nozzle, preventing the build-up of a vacuum. Aninsufficient degree of vacuum in the shared vacuum supply will thus leadto a failure to pick up work-pieces, usually more work-pieces will notbe picked up than just the absent, or inadequately positioned, one.According to the invention therefore the at least one nozzle withindividual vacuum supply is provided. While this nozzle in normaloperation of the pick-and-place head can be used to pick up work-piecesjust as the other nozzles, if a failure of vacuum occurs in the sharedvacuum supply, it can be used to pick up all those work-pieces whichwere not picked up as a result of the insufficient degree of vacuum inthe shared vacuum supply. In this way it is ensured that all work-piecesare picked up. Reconfiguration of the pick-and-place head to change thenumber of nozzles is simpler than in typical heads, as instead ofproviding separate vacuum supplies, in the pick-and-place head accordingto the invention it is sufficient to connect nozzles to or disconnectnozzles from the shared vacuum supply.

In principle it is conceivable, and sufficient to achieve the object ofthe invention, that all nozzles but one are connected to a shared vacuumsupply, and that only one nozzle has an individual vacuum supply. Whilethis configuration is one configuration within the scope of theinvention, many further configurations are possible within the scope ofthe invention.

In one embodiment, the nozzles are arranged in rows. Nozzles withindividual vacuum supplies form a number L, where L is equal to orgreater than one, of these rows. The remaining nozzles form a number Sof rows, where S is equal to or greater than one. The nozzles in each ofthe S rows share a vacuum supply, but the vacuum supply of each such rowis separate from the vacuum supply of all the other rows.

In a different embodiment, the nozzles also are arranged in rows.Nozzles with individual vacuum supplies form a number L, where L isequal to or greater than one, of these rows. The remaining nozzles forma number S of rows, where S is equal to or greater than one. All thenozzles in this number S of rows have a shared vacuum supply, i.e. theyall are connected to a common vacuum supply.

In another embodiment, the nozzles are arranged in rows. At least onenozzle in each row has an individual vacuum supply, and all furthernozzles of the respective row have a shared vacuum supply. Nozzles indifferent rows do not share a vacuum supply. In each of the precedingthree embodiments, each row holds the same number of nozzles. As avariant of each of these embodiments, there are at least two rows ofnozzles which differ between them as to the number of nozzles they hold.

In example embodiments, to each vacuum supply there corresponds a vacuumsensor. The vacuum sensor is configured to indicate whether sufficientvacuum for engaging the work-pieces has been attained or not. Sufficientvacuum has been attained, if the pressure in the interior of a nozzle issufficiently below the environmental pressure so that the work-piece ispressed against the nozzle by the environmental pressure, countering theweight of the work-piece; otherwise the vacuum is insufficient. In thismanner, in case of sufficient vacuum, a nozzle engages a work-piece. Forknown configuration of a nozzle and known weight and geometry of awork-piece, a threshold for a pressure difference between the pressurein the interior of the nozzle and the environmental pressure may beestablished. The vacuum in a vacuum supply, or corresponding nozzle, maythen be deemed sufficient, if the pressure in the vacuum supply ornozzle, respectively, is further below the environmental pressure thanindicated by the threshold. Otherwise the vacuum may be deemedinsufficient. If the vacuum sensor indicates that sufficient vacuum hasnot been achieved, then appropriate measures can be taken. For example,nozzles with individual vacuum supplies can be employed to pick upwork-pieces that were not picked up due to the insufficiency of vacuumin the shared vacuum supply.

In an example embodiment, the nozzles are located on at least one nozzlecarrier mounted on the body of the pick-and-place head. The nozzlecarrier is a separate element of the pick-and-place head and exhibitsthe nozzles of the pick-and-place head. The nozzle carrier can beconnected with the rest of the pick-and-place head. In particular supplylines for the vacuum supply in the body of the pick-and-place head canbe connected to corresponding lines in the nozzle carrier running to thenozzles and thus establishing lines for the vacuum supply of thenozzles. The pick-and-place head is configured such that the nozzlecarrier is exchangeable for a nozzle carrier with a different number ofnozzles. In particular, the supply lines for the vacuum supply withinthe body of the pick-and-place head are configured such that they cancooperate with nozzle carriers having different numbers of nozzleswithout changing the configuration in the body of the pick-and-placehead. In specific embodiments the mounting of the nozzle carrier on thepick-and-place head is via an intermediate element, known as gripperbody, which is connected to the pick-and-place head and contains a mountposition for a nozzle carrier. Nozzle carrier and intermediate element,or gripper body, form a gripper. The gripper body may be moveablerelative to the body of the pick-and-place head.

The pick-and-place head is moveable relative to the plurality ofwork-pieces. In an example embodiment of the above described type wherethe nozzles are arranged in rows the arrangement of the nozzlesfurthermore is such that as the pick-and-place head moves relative tothe plurality of work-pieces the nozzles with individual vacuum supplyfollow the nozzles with shared vacuum supply. In this way work-pieceswhich failed to be picked up by nozzles with shared vacuum supply can bepicked up most easily by the nozzles with individual vacuum supplywithout requiring additional reverse movements of the pick-and-placehead. Such an arrangement of nozzles can be realized whether there isshared vacuum supply for each of a number of rows of nozzles or a vacuumsupply shared by more than one row of nozzles.

As has already been mentioned, the invention can be advantageouslyemployed where the work-pieces handled are electronic components. Inparticular the work-pieces, or electronic components, in embodiments arepicked from at least one tray and placed at a processing station. Theprocessing station may for instance perform assembly, inspection, orpackaging of the work-pieces. The pick-and-place head according to theinvention may also be used to pick the work-pieces at a processingstation and place them into at least one tray.

A particular embodiment of the invention is a pick-and-place head forpicking a plurality of work-pieces from at least one first location andfor placing the plurality of work-pieces in at least one secondlocation. The pick-and-place head exhibits a plurality of nozzles, eachnozzle of the plurality of nozzles configured to engage one of theplurality of work-pieces by action of a vacuum. The nozzles are arrangedin rows, wherein the nozzles of one first row each have an individualvacuum supply and the nozzles of at least one second row have a sharedvacuum supply. A vacuum sensor corresponds to each vacuum supply, eachvacuum sensor configured to indicate whether sufficient vacuum forengaging the work-pieces has been attained or not.

The method according to the invention, for picking a plurality ofwork-pieces with a plurality of nozzles by action of a vacuum, in orderto place the work-pieces at a different location, includes the steps ofapproaching at least one of the plurality of work-pieces with arespective nozzle and starting generation of a vacuum at each respectivenozzle. It should be noted that moving a pick-and-place head in order toengage a work-piece implies movement of all the nozzles of thepick-and-place head, even if in a specific situation there may be atleast one nozzle which will have no work-piece to pick up.

According to the invention the generation of a vacuum in at least one ofthe plurality of nozzles is achieved by an individual vacuum supply ofthe at least one of the plurality of nozzles and generation of a vacuumin at least two further nozzles of the plurality of nozzles is achievedby a shared vacuum supply of the at least two further nozzles. Themeanings of individual vacuum supply and shared vacuum supply havealready been discussed above in the context of the pick-and-place head.

In an advantageous embodiment of the method, in case one or pluralwork-pieces fail to be picked up by nozzles with shared vacuum supply,because there is insufficient vacuum in the shared vacuum supply, suchwork-pieces can be picked up in a subsequent step by nozzles with anindividual vacuum supply. In embodiments the generation of a vacuum ineach vacuum supply, and therefore in the corresponding nozzles, ismonitored by a vacuum sensor provided for each vacuum supply. Eachvacuum sensor is configured to trigger an error signal, if a vacuumsufficient to engage work-pieces by the nozzles connected to itsrespective vacuum supply cannot be achieved.

In some embodiments of the method, the work-pieces are to be picked andplaced with nozzles arranged in rows. Therein, in particular, each rowmay contain the same number of nozzles, but embodiments where there areat least two rows of nozzles which differ in the number of nozzles theycontain are also considered within the scope of the invention. In eithercase, there is a number L, equal to or greater than one, of rows ofnozzles in which each nozzle has an individual vacuum supply. Theremaining nozzles, i.e. those not in the number L of rows justmentioned, are arranged in a number S, equal to or greater than one, ofrows and have a shared vacuum supply. The shared vacuum supply may becommon to all the nozzles in the number S of rows, or may be common onlyto the nozzles of each of the number S of rows, but separate from thevacuum supply of any different row. In these embodiments the methodincludes the steps of attempting to pick up a respective work-piece witheach of the nozzles, then placing the picked up work-pieces at adifferent location, and picking up a work-piece which failed to bepicked up by a nozzle having a shared vacuum supply with a nozzle havingan individual vacuum supply. The step of attempting to pick up awork-piece with a nozzle involves moving the nozzles such that thework-piece or the work-pieces to be picked up are approached by arespective nozzle, contacting the work-piece(s) with the respectivenozzle(s) and starting the generation of a vacuum in the respectivenozzle(s) via the respective connected vacuum supplies. The attempt topick up a work-piece can fail for various reasons: There may be nowork-piece for at least one of the nozzles. In such case, the fact ofnot being able to pick up a non-existent work-piece as such does notconstitute a failure, but if the respective nozzle is connected with avacuum supply shared with other nozzles, then, as there is no work-pieceto block the nozzle, there may not be sufficient vacuum generated in theshared vacuum supply for the other nozzles to pick up work-pieces. Thesame can occur, if there is a work-piece for each nozzle with a sharedvacuum supply, but at least one of these work-pieces is misplaced sothat it cannot fully block the nozzle, again leading to insufficientvacuum in the shared vacuum supply and thus also at the further nozzlesconnected with the shared vacuum supply. The nozzles in the rows ofnozzles with individual vacuum supply, in addition to picking upwork-pieces in a first step, can in a subsequent step or even pluralsubsequent steps pick up work-pieces that failed to be picked up bynozzles connected to a shared vacuum supply.

In a different embodiment, the nozzles are also arranged in rows. Ineach such row a number L, equal to or greater than one, of nozzles eachhave an individual vacuum supply and the remaining number S, equal to orgreater than one, of nozzles in each row have a vacuum supply common tothese S nozzles in each respective row, but separate from the vacuumsupply of nozzles in any different row of nozzles. The method hereincludes the steps of attempting to pick up a respective work-piece witheach of the nozzles, then placing the picked-up work-pieces at adifferent location, and picking up a work-piece which failed to bepicked up by a nozzle having a shared vacuum supply, with a nozzlehaving an individual vacuum supply. The steps of the method correspondto the steps described for the preceding embodiments, the differencehere is in the assignment of nozzles to shared vacuum supplies.

In a particular embodiment of the method according to the invention forpicking a plurality of work-pieces with a plurality of nozzles by actionof a vacuum, in order to place the work-pieces at a different location,the work-pieces and the nozzles are arranged in respective rows. Thenozzles of one first row of nozzles each have an individual vacuumsupply. The nozzles of the remaining at least one second row of nozzleshave a shared vacuum supply. In this embodiment, the method is carriedout as follows:

By relative movement between the nozzles and the work-pieces, each rowof nozzles is positioned above a row of work-pieces. Next, an attempt ismade to pick up a respective work-piece with each nozzle. The attemptcan fail for reasons already discussed above. Work-pieces which havebeen picked up are then placed at a desired different location. Theembodiment of the method also includes a step of verifying ifwork-pieces failed to be picked up in the attempt just mentioned. Thiscan for example be achieved by vacuum sensors for the vacuum supplies ofthe nozzles. Insufficient vacuum detected in a shared vacuum supply willthen trigger the steps described below with respect to the rows ofwork-pieces which the rows of nozzles corresponding to the shared vacuumsupply with insufficient vacuum attempted to pick up.

In order to pick up work-pieces which failed to be picked up before, thefirst row of nozzles is positioned over a work-piece which failed to bepicked up. The work-piece is then picked up with a nozzle of the firstrow of nozzles and placed at the desired different location. If morethan one work-piece failed to be picked up from a specific row ofwork-pieces, which can easily occur if the shared vacuum supply for therow of nozzles intended to pick up the specific row of work-piecesfailed to provide sufficient vacuum, then all such work-pieces can bepicked up in one step by the first row of work-pieces. The first row ofnozzles proceeds to pick up any work-pieces for which the attempt topick them up failed, and to place those work-pieces at their respectivedesired locations. If this is completed or if there were no failedattempts to pick up work-pieces, it is tested whether at least as manyrows of work-pieces remain to be picked up as there are rows of nozzles.If so, the rows of nozzles are advanced relative to the rows ofwork-pieces and the steps just described are repeated. In case of aninsufficient number of rows of remaining work-pieces the remaining rowsof work-pieces can for example be picked up with the nozzles of thefirst row of nozzles.

These and other objects, advantages and features of the presentinvention will be better appreciated by those having ordinary skill inthe art in view of the following detailed description of the inventionin view of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The nature and mode of operation of the present invention will now bemore fully described in the following detailed description of theinvention taken with the accompanying drawing figures, in which:

FIG. 1 is a schematic representation of a pick-and-place device with apick-and-place head;

FIG. 2 is a schematic representation showing a plurality of nozzles withindividual and shared vacuum supplies according to an embodiment of theinvention;

FIG. 3 is a schematic representation showing an arrangement of nozzleswith shared and individual vacuum supplies according to an embodiment ofthe invention;

FIG. 4 is a schematic representation showing an arrangement of nozzleswith shared and individual vacuum supplies according to a furtherembodiment of the invention;

FIG. 5 is a schematic representation showing an arrangement of nozzleswith shared and individual vacuum supplies according to a furtherembodiment of the invention;

FIG. 6 is a schematic representation showing a nozzle carrier with twonozzles having an individual vacuum supply, the nozzle carrier attachedto an element of a pick-and-place head;

FIG. 7 is a schematic representation showing a nozzle carrier with onenozzle having an individual vacuum supply and two nozzles having ashared vacuum supply, the nozzle carrier attached to an element of apick-and-place head;

FIG. 8 is a flow diagram of an embodiment of the method to pick andplace work-pieces; and,

FIG. 9 is an illustration of an embodiment of the method, showingvarious steps of the picking of work-pieces.

DETAILED DESCRIPTION

At the outset, it should be appreciated that like drawing numbers ondifferent drawing views identify identical, or functionally similar,structural elements of the invention. While the present invention isdescribed with respect to what is presently considered to be thepreferred aspects, it is to be understood that the invention as claimedis not limited to the disclosed aspect. Also, it is to be understoodthat the invention is not limited in its application to the details ofconstruction and the arrangement of the components set forth in thefollowing description or illustrated in the drawings. The invention isapplicable to other embodiments or of being practiced or carried out invarious ways and is intended to include various modifications andequivalent arrangements within the spirit and scope of the appendedclaims.

Furthermore, it is understood that this invention is not limited to theparticular methodology, materials and modifications described and assuch may, of course, vary. It is also understood that the terminologyused herein is for the purpose of describing particular aspects only,and is not intended to limit the scope of the present invention, whichis limited only by the appended claims.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which this invention belongs. Although any methods, devicesor materials similar or equivalent to those described herein can be usedin the practice or testing of the invention, the preferred methods,devices, and materials are now described.

In the below description, an embodiment is an example or implementationof the invention. The various appearances of “one embodiment”, “anembodiment”, “certain embodiments” or “some embodiments” do notnecessarily all refer to the same embodiments.

FIG. 1 shows pick-and-place device 1 having pick-and-place head 2.Pick-and-place head 2 is moveable, as indicated by double arrow A, alongrail 3, in order to pick work-pieces 4 from tray 5 and place them atprocessing station 6. Pick-and-place head 2 with picked up work-pieces 4is shown again in dashed lines in a position over processing station 6.Pick-and-place head 2 engages work-pieces 4 by nozzles 10. Nozzles 10engage work-pieces 4 by action of a vacuum. In pick-and-place head 2 thenozzles are therefore connected to corresponding vacuum supplies (notshown in FIG. 1). In prior art, each nozzle has a separate vacuumsupply. According to the invention, at least one nozzle 10 has aseparate vacuum supply and at least two further nozzles 10 have a sharedvacuum supply. In example embodiments, nozzles 10 can be moved in adirection, indicated by double arrow B, perpendicular to the directionindicated by double arrow A, in order to lift work-pieces out of thetray and also in order to place them onto processing station 6. Indifferent embodiments, rail 3 may be moveable in the direction indicatedby double arrow B. A pick-and-place head according to the invention canalso be employed in pick-and-place devices of different configuration,for example, the pick-and-place head may be mounted on a robotic arm.

FIG. 2 shows a plurality of nozzles 10. Some of nozzles 10 have anindividual vacuum supply 11L, while further nozzles 10 have sharedvacuum supply 11S. In particular, FIG. 2 shows three rows of threenozzles 10 each, wherein one nozzle 10 of each row has individual vacuumsupply 11L, and the remaining two nozzles 10 of each row have sharedvacuum supply 11S. In this embodiment there is no vacuum supply sharedbetween rows of nozzles.

FIG. 3 is a schematic representation of nozzles 10, shown as filledblack circles, and the connectivity of the vacuum supplies of nozzles10. The vacuum supplies are shown as lines. More precisely, in FIG. 3four rows of nozzles 10 are shown, each row containing six nozzles 10.The nozzles of one of the rows each have individual vacuum supply 11L,while for the remaining three rows of nozzles 10, each row has sharedvacuum supply 11S, common to all nozzles 10 of the respective row, butseparated from the vacuum supplies of all the other rows of nozzles 10.

FIG. 4 shows a different connectivity of the vacuum supply of nozzles10, using the same schematic representation as FIG. 3. FIG. 4 shows fourrows of nozzles 10, each row containing six nozzles 10. The nozzles ofone of the rows each have individual vacuum supply 11L, while theremaining three rows of nozzles 10 have shared vacuum supply 11S, commonto all nozzles 10 of the three rows.

FIG. 5 shows yet another connectivity scheme of the vacuum supply ofnozzles 10, using the same schematic representation as FIG. 3. FIG. 5shows six rows of nozzles 10, each row containing four nozzles 10. Onenozzle 10 of each row has individual vacuum supply 11L, while theremaining three nozzles 10 of each row have shared vacuum supply 11S. Novacuum supplies are shared between rows.

For all embodiments, the vacuum supplies comprise pipes, tubes, channelsultimately connected to a known source of vacuum like one or pluralpumps of known type, where the source of vacuum is configured to removegas, in particular air, from the pipes, tubes, channels and thus alsofrom the interior of nozzles 10 forming an end of the pipes, tubes,channels. If nozzle 10 is blocked by a work-piece, then no gas/air canenter the nozzle to replace the removed gas/air, and a vacuum isgenerated in the nozzle; in the context of the application generation ofa vacuum means generation of a pressure of the gas/air lower than theenvironmental pressure. A sufficient degree of vacuum is achieved, ifthe pressure difference between the environmental pressure and thepressure in the nozzle is sufficient to counter the weight of awork-piece to be picked up, so that the work-piece is pressed againstthe nozzle.

FIG. 6 shows an element, often referred to as gripper 20, which exhibitsnozzles 10 and by which nozzles 10 are attached to pick-and-place head 2as shown in FIG. 1. In the embodiment shown, gripper 20 comprises nozzlecarrier 21, also known as pitch adaptor, and gripper body 23, connectedto nozzle carrier 21 by connection means 22. In pick-and-place head 2ready for operation, gripper body 23 is mounted to the body of pick- andplace head 2, which includes connecting each of channels 11 to aseparate vacuum source. In the embodiment shown, nozzle carrier 21 canbe detached from gripper body 23. When nozzle carrier 21 is attached togripper body 23, connecting means 22 not only mechanically secures theconnection between gripper body 23 and nozzle carrier 21, but alsoestablishes a connection for channels 11 from gripper body 23 to nozzlecarrier 21. In the embodiment shown, each channel 11 leads to one nozzle10. As each channel 11 is connected to a separate vacuum source, as hasbeen stated, each of the two nozzles 10 shown has an individual vacuumsupply, which is established by one of channels 11, respectively. In theembodiment shown, nozzle carrier 23 may be exchanged for a differentone.

FIG. 7 also shows gripper 20. The same gripper body 23 as shown in FIG.6 is used, but by connecting means 22 a different nozzle carrier 23 isattached to gripper body 23. Nozzle carrier 21 of FIG. 7 exhibits threenozzles 10 instead of two, but, as can be seen from FIG. 7, theconfiguration of gripper body 23 has not changed. Still each of channels11 is connected to a separate source of vacuum. By the configuration ofnozzle carrier 21, one of channels 11 establishes an individual vacuumsupply for one of nozzles 10, while the other channel 11 establishes ashared vacuum supply for the remaining two nozzles 10.

The gripper body of FIG. 6 and FIG. 7 may be configured such and mountedto pick-and-place head 2 in such a manner that it can be moved relativeto the pick-and-place head along the direction indicated by double arrowB in FIG. 1. This configuration and mounting of gripper body 23 isindependent of nozzle carrier 21 used, in particular of the number ofnozzles 10 present on nozzle carrier 21. For placing FIGS. 6 and 7 intocontext, one nozzle 10 is shown with work-piece 4 engaged.

FIG. 8 is a flow chart of a specific embodiment of the method accordingto the invention. In this embodiment, a pick-and-place head with threerows of nozzles is used, each row of nozzles having the same number ofnozzles. The nozzles of a first one of the rows of nozzles each have anindividual vacuum supply, and the nozzles of the remaining two rows havea shared vacuum supply. The description of the method provided by theflow chart applies both if the shared vacuum supply is connected betweenthe two rows and if the vacuum supply is shared between the nozzles ofthe respective row only. Furthermore, the work-pieces are aligned inrows as well, the distance between subsequent rows of work-piecescorresponding to the distance between the rows of nozzles on thepick-and-place head used, so that three rows of work-pieces can bepicked up at once. The pick-and-place head with the nozzles is moveablerelative to the work-pieces, such that the row of nozzles withindividual vacuum supplies, i.e. the first row of nozzles, follows therows of nozzles with the shared vacuum supply.

In step 100, by relative movement between the pick-and-place head andthe work-pieces, the three rows of nozzles are placed over three rows ofwork-pieces, one row of nozzles over one row of work-pieces,respectively. Usually, the nozzles are brought in contact with thework-pieces to be picked up.

In step 105, it is attempted to pick up the work-pieces over whichnozzles are positioned, simultaneously in a single step, by starting thegeneration of a vacuum in the respective vacuum supply of each nozzle.

In step 110, the picked up work-pieces are placed at a desired differentlocation, for example a processing station.

In step 115 it is checked whether there are any work-pieces which failedto be picked up in step 105. This checking can be done by any suitablemeans, for example the rows of work-pieces could be monitored by camerasand image processing could be used. Alternatively, each vacuum supply isprovided with a vacuum sensor. Such a vacuum sensor is configured totrigger an error signal if only an insufficient vacuum is attained inits corresponding vacuum supply. The meaning of insufficient vacuum hasbeen explained above. In such a case there will be work-pieces whichfailed to be picked up in step 105. If this is the case, branch ‘Y’ inFIG. 8, the method proceeds with step 120. If this is not the case, i.e.if there are no work-pieces which failed to be picked up in step 105,the method proceeds with step 135, branch ‘N’ from step 115.

In step 120, the first row of nozzles is positioned over a work-piecewhich failed to be picked up, i.e. it is positioned over the location arow of work-pieces, from which at least one work-piece failed to bepicked up in step 105, occupied before step 105. In step 125, the atleast one work-piece which failed to be picked up in step 105 is pickedup with a nozzle from the first row of nozzles. If more than onework-piece from the respective row failed to be picked up in step 105,then all these work-pieces are picked up simultaneously by the nozzlesof the first row of nozzles in one step. The picked up work-pieces arethen placed at their corresponding desired different location.

In step 130, it is checked, whether any work-pieces which failed to bepicked up in step 105 remain. This can in particular occur, ifwork-pieces from more than one row of work-pieces failed to be picked upin step 105. If this is the case, branch ‘Y’ from step 130, the methodreturns to step 120. If this is not the case, branch ‘N’ from step 130,the method proceeds with step 135.

If step 135 is reached, all work-pieces that were to be picked up instep 105 have been picked up and placed at their respective desiredlocation, either directly by steps 105 and 110, or via additional steps120 and 125. The method then can proceed to pick up any potentialfurther rows of work-pieces.

In step 135, it is tested whether any rows of work-pieces remain. If no,branch ‘T’ from step 135, the method terminates. It is also testedwhether at least as many rows of work-pieces remain to be picked up asthere are rows of nozzles, i.e., at least three rows of work-pieces inthe specific embodiment described here, and if so, branch ‘Y’ from step135, the pick-and-place head is advanced by three rows of work-pieces,to repeat the steps of the method from step 100. If fewer rows ofwork-pieces, i.e., fewer than three rows of work-pieces in the specificembodiment described, remain, any remaining rows of work-pieces can bepicked up by the nozzles of the first row, as if they had failed to bepicked up in step 105; therefore, in this case, the method will considerthe remaining rows of work-pieces as if they had failed to be picked upand proceed with step 120, branch ‘N’ from step 135.

FIG. 9 illustrates the method by showing rows of work-pieces at variousstages of the method. The stages are indicated, in the order they occurin the method, by letters a, b, c, and d. As in FIGS. 3, 4, and 5,filled dots indicate nozzles 10, lines between nozzles indicate a sharedvacuum supply. For ease of reference, the rows of work-pieces are namedR1, R2, R3, R4, R5, R6, and R7. Crossed squares indicate work-piece 4,while empty squares indicate a position in a row which could be occupiedby a work-piece, but is empty, or a position where a work-piece ismisplaced.

At the start, stage a, rows R1, R2, and R3 are to be picked by nozzles10, row R1 is to be picked by nozzles 10 with individual vacuum supply,while rows R2 and R3 are picked by the nozzles with shared vacuumsupply. All positions in rows R1, R2, R3 are occupied by correctlyplaced work-pieces, so all work-pieces can be picked up simultaneously,and then placed at their desired location elsewhere, for instance aninspection or assembly station. The positions the work-pieces occupiedin the rows here then are empty. Depending on the manufacturing process,it is possible that after a step, like inspection, for which thework-pieces were picked from the rows, they are placed back into therows, before the next rows of work-pieces are picked. In this case, thepositions in rows R1, R2, R3 would not be empty, but occupied again. Themethod moves to stage b. The rows of nozzles 10 are advanced by threerows of work-pieces, so thin at stage b rows R4, R5, and R6 are to bepicked, more precisely row R4 by the row of nozzles 10 with individualvacuum supply, rows R5 and R6 with the rows of nozzles 10 with sharedvacuum supply.

All work-pieces in row R4 can be picked by the nozzles with individualvacuum supply. In row R5, however, there is an empty position. In theshared vacuum supply, due to the empty position in row R5, no sufficientvacuum can be obtained, as the corresponding nozzle over the emptyposition is not sealed by a work-piece. In this example, theinsufficient vacuum results in all the work-pieces of rows R5 and R6 notbeing picked. The work-pieces picked by the nozzles with individualvacuum supplies, i.e. those work-pieces picked from row R4, are placedat their desired location. The method then proceeds to stage c.

In stage c, the rows of nozzles with individual vacuum supplies areplaced over row R5. The nozzles with individual vacuum supplies pick upthe three work-pieces in row R5. The fact that due to the missingwork-piece no sufficient vacuum can be obtained in one of the nozzlesoperating on row R5 does not affect the vacuum in the other nozzles,precisely because their vacuum supplies are independent of each other.Depending on how the pick-and-place head is operated, in stage c, asrows R6 and R7 are complete, i.e. no work-pieces are missing, these rowscould also be picked up at this step, and the work-pieces from rows R5,R6, and R7 could be placed at their desired location. The method thenwould stop, as all work-pieces have been transferred to a differentlocation. Alternatively, and corresponding to the embodiment of themethod discussed in the context of FIG. 8, the method, at stage c, couldproceed to pick up only the work-pieces from row R5 and place them attheir desired location. The method could then proceed to pick up thework-pieces in the remaining rows R6 and R7 by the nozzles withindividual vacuum supply only.

In the latter alternative, the method proceeds to step d, in order topick the work-pieces from row R6, which will be placed at their desiredlocation. After the obvious and not shown operation of moving thenozzles with individual vacuum supplies to row R7 and repeating thepicking and placing with the work-pieces of row R7, the method hasfinished, all work-pieces from rows R1 to R7 have been transferred tothe desired location.

The invention is not limited to those diagrams or to the correspondingdescriptions. For example, flow need not move through each illustratedbox or state, or in exactly the same order as illustrated and described.

Thus, it is seen that the objects of the present invention areefficiently obtained, although modifications and changes to theinvention should be readily apparent to those having ordinary skill inthe art, which modifications are intended to be within the spirit andscope of the invention as claimed. It also is understood that theforegoing description is illustrative of the present invention andshould not be considered as limiting. Therefore, other embodiments ofthe present invention are possible without departing from the spirit andscope of the present invention as claimed.

What is claimed is:
 1. A pick-and-place head configured tosimultaneously transport a plurality of separate work-pieces from atleast one first location to at least one second location, thepick-and-place head comprising: a plurality of nozzles with each nozzleconfigured to engage a separate one of each of the plurality of separatework-pieces, the plurality of nozzles arranged in a plurality of rowswith at least a first and second row; a first vacuum supply connected toat least one nozzle in the first row or the second row and configured togenerate a vacuum at the at least one nozzle in the first row or thesecond row; a second vacuum supply connected to at least two nozzles inthe first row or in the second row and configured to generate a vacuumat the at least two nozzles in the first row or the second row; aplurality of vacuum sensors configured to indicate whether a sufficientforce is being applied to the plurality of work-pieces; wherein, thefirst and second vacuum supplies are configured to separately generate avacuum such that each nozzle of the plurality of nozzles is configuredto separately engage a respective work-piece amongst the plurality ofwork-pieces.
 2. The pick-and-place head as recited in claim 1,comprising a plurality of first vacuum supplies, wherein each of theplurality of first vacuum supplies is configured to separately attach toeach nozzle of the plurality of nozzles in the first row.
 3. Thepick-and-place head as recited in claim 1, wherein the second vacuumsupply and the first vacuum supplies have one vacuum sensor.
 4. Thepick-and-place head as recited in claim 1, wherein the pick-and-placehead is moveable relative to the plurality of work-pieces.
 5. Thepick-and-place head as recited in claim 4, wherein the arrangement ofthe rows of nozzles on the pick-and-place head is such that as thepick-and-place head moves over the plurality of work-pieces in a defineddirection, the first row follows the second row.
 6. The pick-and-placehead as recited in claim 1, wherein: the plurality of rows furthercomprises a third row; and, the second vacuum supply is configured toattach to the plurality of nozzles in the third row.
 7. Thepick-and-place head as recited in claim 1, comprising a plurality offirst vacuum supplies, wherein at least one nozzle in at least one rowis connected to one of the plurality of first vacuum supplies and allfurther nozzles of the respective row are connected to the second vacuumsupply.
 8. The pick-and-place head as recited in claim 1, wherein theplurality of nozzles are arranged on at least one nozzle carrier mountedto a body of the pick-and-place head.
 9. The pick-and-place head asrecited in claim 8, wherein the at least one nozzle carrier isexchangeable for another nozzle carrier with a different number ofnozzles, with such an exchange not requiring a change to a vacuum supplywithin the body of the pick-and-place head.
 10. The pick-and-place headas recited in claim 1, wherein the plurality of work-pieces areelectronic components.
 11. The pick-and-place head as recited in claim1, wherein the plurality of work-pieces are picked from at least onetray and placed at a processing station and/or picked at a processingstation and placed onto at least one tray.
 12. A method configured tosimultaneously pick a plurality of separate work-pieces with a pluralityof nozzles by action of a vacuum, and place the separate work-pieces ata different location, the method comprising the steps of: approaching atleast one of the plurality of separate work-pieces with a separaterespective nozzle; and, simultaneously generating a vacuum at eachrespective nozzle; wherein the generating step is: achieved in at leastone of the plurality of nozzles by a first vacuum supply that isconnected to the at least one of the plurality of nozzles, and in atleast two further nozzles of the plurality of nozzles by a second vacuumsupply that is connected to the at least two further nozzles; and,monitored by a vacuum sensor provided for each of the first and secondvacuum supplies, and an error signal is triggered, if in one of thefirst and second vacuum supplies a vacuum sufficient to engagework-pieces by the nozzles connected to the vacuum supplies cannot beachieved.
 13. The method as recited in claim 12, wherein a work-piecefailing to be picked up by one of the at least two further nozzleshaving the second vacuum supply is subsequently picked up by one of theat least one of the plurality of nozzles having the first vacuum supply.14. The method as recited in claim 12, wherein the plurality of nozzlesare arranged in rows, the nozzles in a number L of rows each having arespective first vacuum supply, the number L being greater than or equalto one, and the nozzles in the remaining number S of rows having thesecond vacuum supply common to all the nozzles in the number S of rows,the number S being greater than or equal to one, the method comprisingthe steps of: a) attempting to pick up a respective work-piece with eachof the nozzles; b) placing the picked-up work-pieces at a differentlocation; and, c) picking up a work-piece which, in step a), failed tobe picked up by a nozzle having the second vacuum supply, with a nozzlehaving the respective first vacuum supply.
 15. The method as recited inclaim 12, wherein the plurality of nozzles are arranged in rows, thenozzles in a number L of rows each having a first vacuum supply, thenumber L being greater than or equal to one, and the nozzles in each ofthe remaining number S of rows having a second vacuum supply, separatefrom a vacuum supply of any different row of nozzles, the number S beinggreater than or equal to one, the method comprising the steps of: a)attempting to pick up a respective work-piece with each of the nozzles;b) placing the picked-up work-pieces at a different location; and, c)picking up a work-piece which, in step a), failed to be picked up by anozzle having the second vacuum supply, with a nozzle having the firstvacuum supply.
 16. The method as recited in claim 12, wherein theplurality of nozzles are arranged in rows, a number L of nozzles in eachrow connected to at least one first vacuum supply and the remainingnumber S of nozzles in each row connected to at least one second vacuumsupply common to the remaining S nozzles but separate from a vacuumsupply of nozzles in any different row of nozzles, the number L beinggreater than or equal to one, the number S being greater than or equalto one, the method comprising the steps of: a) attempting to pick up aplurality of separate respective work-pieces with the plurality ofnozzles, each of the plurality of nozzles arranged so as to correspondto a respective one of the plurality of workpieces to be picked up; b)placing the picked-up work-pieces at a different location; and, c)picking up a work-piece which, in step a), failed to be picked up by anozzle having the second vacuum supply, with a nozzle having the firstvacuum supply.
 17. A method for picking a plurality of work-pieces witha plurality of nozzles by action of a vacuum, for placing thework-pieces at a different location, wherein the plurality ofwork-pieces and the plurality of nozzles are arranged in respectiverows, nozzles of one first row of nozzles each having an individualvacuum supply, the nozzles of the remaining and at least one second rowof nozzles having a shared vacuum supply, the method comprising thesteps of: a) positioning, by relative movement between the nozzles andthe work-pieces, each row of nozzles above a row of work-pieces; b)attempting to pick up a respective work-piece with each nozzle; c)placing the picked-up work-pieces at a different location; d) verifyingif work-pieces failed to be picked up in step b); e1) positioning thefirst row of nozzles over a verified work-piece that has been verifiedby step d) as being failed to be picked up; f1) picking up the verifiedwork-piece with a nozzle of the first row of nozzles and placing theverified work-piece at the different location intended for it in stepc); g1) repeating steps e1) and f1) until no verified work-pieces whichfailed to be picked up in step b) remain; e2) testing, if step d) doesnot indicate work-pieces that failed to be picked up, if at least asmany rows of work-pieces remain to be picked up as there are rows ofnozzles, and if so, repeat from step a), else consider any remainingrows of work-pieces as if they had failed to be picked up in step b) andproceed from step e1), picking up all the work-pieces in such a row withthe nozzles in the first row of nozzles.